Thermodynamically-controlled socket-switch for electric lights



M. H. BAKER, DECD.

M. H. BAKER. ADMINISTRATRIX.

THERMODYNAMICALLY CONTROLLED SOCKET SWITCH FOR ELECTRIC LIGHTS. APPLICATION FILED ocr. 25. I915. RENEWED APR. I4. I919.

1, 350,587, Patented Aug. 24, 1920.

n liliiii UNITED STATES JPATENT OFFICE.

MALCOLM. H. BAKER, OF BRAINTREE, MASSACHUSETTS, MARIE H. BAKER, ADMINIS- TRATRIX 01E SAID MALCOLM H. BAKER, DECEASED, ASSIGNOR TO KENNETH CROSBY, TRUSTEE, OF BOSTON, MASSACHUSETTS.

THERMODYNAMICALLY-CONTROLLED SOCKET-SWITCH FOR ELECTRIC LIGHTS.

Specification of Letters Patent.

Patented Aug. 24, 1920.

Application filed October 25, 1915, Serial No. 57,879. Renewed April 14, 1919. Serial No. 290,08).

ratchet driven switch for electric circuits wherein successive movements of an oscillatory drive member in the same dlrectlon,

alternatelyclose and open the switch circuit,

and wherein automatic thermo-dynamically controlled switch opening mechanism is incorporated, arranged and constructed so that the switch is closed in the usual manner-by a single oscillation of the drive member but wherein the next succeeding oscillation of said member operates to place the switch under the control of the said automatic opening mechanism, so that the switch circuit is opened a predetermined time after the occurrence of said second or succeeding osc llation of the drive mechanism.

As illustrated herein, my invention provides novel means for controlling and energizing such automatic opening mechanism, or device, by a circuit in shunt to the switch controlled load, such as a lamp ;and, par ticularly in socket switch structures where the size of parts and of the entire structure is necessarily limited, my invention provides a novel arrangement and disposition of the heating circuit for the automatic control, as necessarily comprised in a shunt arranged resistance such as herein described.

In carrying out my invention I provide my novelly controlled socket switch with the usual threaded lamp receptacle at one end, and preferably with some form of spring-returned pull-chain control mechanism.

In the particular embodiment of my invention, herein disclosed for illustrative purposes only the pull-chain controls an oscillatory wheel device which is loosely mounted upon a shaft, and the said shaft carries, fixed to it, a ratchet wheel which is engaged and rotated substantially 90, by a catch mounted upon the said. wheel device, at each pull of the chain. Spring means are provided to oppose the pull of the chain and to rotate the wheel device back to its original position when the chain is released, and guide detent mechanism is mounted upon the shaft to position it accurately at the end of each 90 increment given by the chain control. The shaft also carries, fixed to it,

a key which engages a resiliently mounted contact and forces the latter into engagement with a cooperative contact to close the circuit through the'switch, the said resiliently mounted contact being tensioned normally to separate from the said cooperative contact, but being maintained continuously in operative engagement'therewith by the key. The above described action takes place under a pull of the chain adapted to close the switch.

Upon the next, or succeeding, pull of the chain the key is rotated by the shaft so as to release the resiliently mounted contact which tends to move away from the cooperative contact, but whichis prevented from leaving the latter by a thermo-dynamically controlled detent interposed in the path of movement of said resiliently mounted contact when the thermostat is normally cool. In'order to maintain secure operative contact the said cooperative contact is also resiliently mounted so as to follow up the first mentioned contact until same is engaged and held by the detent. At the same time the movement of the key has energized an electric heater for the thermostat by connecting same in shunt to the switch controlled load. This energizes the thermostat, or other form of thermo-dynamic control of the thermodynamic device, and moves the detent to release the related contact, which then separates from the cooperative contact with a snap action. The switch circuit and the electric heater circuit are now both broken.

In order to arrange the operative parts of my invention within the close limits required for a socket structure of the ordinary incandescent lamp I am obliged to arrange the heating winding of the thermostat in the manner best adapted to the confined working space. In order to avoid excessive generation of heat, which either produces a too rapid operation. of the opening mechanism or else raises the temperature of the thermostat to a degree necess tating the brazing together of the two metals of the said thermostat, aside from injuring the parts otherwise, I am under the necessity of employing a suficient length of the smallest available resistance wire of the highest spe cific resistance to be had. Experiments show that about three or four feet of No. 40 Nichrome resistance wire must, at least, be used, and T find it impractical to wind such an amount directly upon the thermostat on account of the rapid action imparted or ex: cessive heat given thereto. 1 therefore wind a portion only of this resistance upon the thermostat and wind the rest at some other location in the socket structure, the prefer able place being around the threaded receptacle carrying the lamp bulb base. 'Or ll may otherwise dispose of the extra length of resistance, as later set forth.

I have illustrated my invention the annexed drawings, in which Figure 1 is a sectional view, taken in section on the hue A--A of Fig. 7 and showing the parts as when the switch is closed and in normal operation. Fig. 2 is a similar view but showing the switch open. Fig. 3 1s a plan view of the switch with the cover removed, and Fig. 4 is a section taken on the line BB of Fig. 7. Fig. 5 is a section on the line.CC of Fig. 7 Fig. 6 is an elevation of the complete switch, and Fig. 7 is a section on the line D-D of Figs. 1, 4, and 5. Fig. 8 is a plan, enlarged, of certain details, Fig. 9 is a detail showing a modified form of thermostatic control, Fig. 10 a section on the line EE of Fig. 8, Fig. 11 a diagram of the electrical connections of the switch, and Fig. 12 a front elevation of Fig. 9.

In the drawings, the pull chain appears at 1 and is attached to a wheel 2 loosely mounted upon a shaft 3 uided in a bracket 4 mounted upon a top piece 5 and a bottom piece 6 of insulating material.

The wheel 2 carries, pivoted to it, a dog, or catch, 7 adapted to engage, while the wheel is being rotated by a pull on the chain 1, with a ratchet wheel 8 fastened to the shaft 3, so that said shaftis rotated 90 for each pull of the chain. The shaft 3 also carries a detent member of cam form 9 engaged by a spring 10, so that the shaft is yieldingly locked in place at the end of each 90 increment. A helical spring 11 is attached at one end to a stud 12 in the top piece 5 and at the other end to the catch 7, so that said spring performs the double function of holding the catch 7 against the ratchet wheel 8 and of opposing the pull action of the chain on the loose wheel 2. Suitable insulation is introduced between the wheel 2 and the shaft 3, as shown.

A key 13 is attached to the shaft 3.and engages with a contact 14 resiliently mounted to the bracket 4 and tensioned normally to separate frem a cooperative contact 15 mounted resiliently upon a bracket 16 at- Lamas"? tached to the pieces 5,-6. An auxiliary contact 17 is resiliently mounted to a bracket 18 on the pieces 5, 6, and is engaged by one end of the key 13 when the same is moved out of engagement with the contact 14. A thermostat 19, having a winding 20, is mounted upon the bracket 4 and has an inturned end 21 lying normally in the path of movement of the end ofthe contact 14.

The threaded receptacle adapted to receive the lamp base appears at 22, and is encompassed by a drum of some suitable insulating material and wound with resistance wire 23. The resistance Wire 23 in series with the thermostat winding 20 is contained in a switch-governed circuit directly across the supply line in shunt to the lamp as plainly shown in Fig. 11,the additional resistance thus interposed cutting down the current consumption so that the heat generated in the winding about the thermostat will not be excessive. The said wire is then covered with another layer of insulating material to protect it from the usual casing 24.

It will be seen that the mounting, assemblage and connection of the resistance in this manner (here employed in connection with agoverning thermostat) furnishes a novel and advantageous means of providing a resistance unit as part of a socket-switch and to be employed with the switch-governed circuits. While the resistance is well mounted as part of the socket-switch structure, it is capable of ready removal with the structure, from the telescopically-engaging case without change in the latter ;and at the same time leaves the switch mechanism, etc., exposed for ready inspection, etc., without disturbance of the resistance unit or the connections.

A stop 25 is provided to limit the movement of the wheel 2, said stop being mounted upon the top piece 5.

The cover portion of the casing appears at 26 and the usual binding posts for the line wires at 27.

In Figs. 9 and 12 a modified form of thermostat is shown. Here no winding is placed upon the thermostat proper, but the same is mounted upon a thermally conductive block, preferably of copper, which itself carries the resistance winding. Heat is conducted from this block to the thermostat to operate the same in the usual manner. The block is shown at 28, the winding at 29, and the thermestat at 30.

It will be noted that current passes, during energization of the resistance winding, from the key bracket to the key, and to avoid loose contacts and burning of parts I generally locate a spring washer 31 so as to maintain the key 13 pressed against the bracket 4, or rather against a loose copper washer placed between said key and said bracket.

Operation is as follows, starting from the open position of the switch,when the chain 1 is pulled the wheel 2 is rotated 90 against the action of the spring 11. This causes the ratchet wheel 8 to move 90 and therewith the key 18, which thus moves the contact 14 up past the thermostat end (the latter springing slightly to permit such passage) and into contact with the member 15,

where it is maintained by the said key. The switch is now closed for normal operation.

To open the switch the chain 1 is again pulled, which againfrotates the wheel 2 90 and thus moves the key 13 out of engagementwith the member 14 and into engagement with the member 17. This closes a shunt circuit across the switch load and through the thermostat resistance 20 and the auxiliary resistance 23, which former energizes the thermostat to cause same to release the member letto open'the circuit.

The time interval elapsing between the second actuation of the chain and the opening of the switch is the time required to heat to operation the thermostat, and may of course be varied in many ways,-as by an alteration in the amount of resistance, size of thermostat, engagement of same with the governed member, etc;

YVith the form shown in Figs. 9 and 12 the thermostat winding may develop a high degree of heat without operating the thermostat too rapidly, since time is required for the copper block,'upon which the resistance is wound, to heat, and then to transmit heat to the thermostat. Of course this form cannot be so compact as the preferred form in which a portion of the resistance is located as shown.

Either of the two means herein set forth,--that is, placing some of the resist ance winding externally independent of the thermostat, or .placing said winding on a separate heating block, may be employed, the former, as stated, being preferable, and practically needful to keep the socket switch down to the least dimensions.

.It is of-course apparent that within the scope of my invention I may embody the pull-chain ratchetcontrol mechanism in forms other than the illustrative example herein disclosed and that I may combine such mechanism with a switch embodying a different arrangement of contacts and of thermo -dynamic means for delaying the opening thereof than I have herein shown.

Without, therefore, confining myself to the exact embodiment of the invention herein shown, what I claim is 1 In an electric circuit switch, the combination with automatic switchopening mechanism embodying main circuit controlling contacts tensioned normally to separate and a latch and controlling thermostat therefor positioned when the thermostat is thermally deenergized to prevent separation of said contacts and then thermally energized to permit said separation, of a pivoted switch-controlling member progressively rotatable into alternate switch-closing and switch-opening positions thereof and adapted in said switch-closing position to close said contacts, a manually operable oscillatory device arranged as a ratchet andv upon consecutive actuations thereof to drive said member from one to another of its said positlons, and an electric heater for the thermostat, together with auxiliary circuit governing means for controlling said heater and arranged to be operated by said'member,-whereby movement of said member to its said switch-opening position renders said heater operative thermally to energize the thermostat.

2. In an electric circuit switch, the combination with automatic switch-opening thereof to drive said memberfrom one to another of its said positions, and an electric heater for the thermostat, together with auxiliary circuit governing means for controlling said heater and arranged to be operated by said member,-whereby. movement of said member to its switch-opening position renders said heater operative thermally to energize the thermostat.

3. In an electric circuit switch, the combination with automatic switch-opening mechanism embodying main circuit controlling contacts tensioned normally to separate and a latch and controlling thermostat therefor positioned when the thermostat is thermally de'e'nergized to prevent separation of said contacts and when thermally energized to permit said separation of a pivoted switch-controlling member'progressively rotatable into alternate switch-closing and switch-opening positions thereof and adapted in said switch-closing position to close said contacts, a manually operable oscillatory device arranged as a ratchet and upon consecutive actuations thereof, to drive said member from oneto another of its said positions, and an electric heater for the thermostat, together with auxmechanism for automatically governing the same including a thermostatically controlled detent with an electric heater for the thermostat thereof arranged to be connected in shunt to the switch controlled circuit, a holding member below the lower holding plate for connecting the switch load, an auxiliary resistance in series with the said heater and wound upon said holding member, and an outer protecting structure 'surrounding the switch and the said auxiliary winding.

5. In an electric circuit switch, the combination with automatic switch-opening mechanism embodying main circuitcon-' trolling contacts tensioned normally to separate'and a latch and controlling thermostat therefor positioned when the thermostat is thermally deenergized to prevent separation of said contacts and when thermally energized to permit said separation, of a pivoted switch-controlling member progressively rotatable into alternate switchclosing and switch-opening positions thereof and adapted in said switch-closing position to close said contacts, a manually operable oscillatory device arranged as a ratchet and upon consecutive actuations thereof to drive said member from one to another of its said positions, and an electric heater for the thermostat having a separate and thermally remote rheostat in series therewith for reducing the current therethrough, together with auxiliary circuit governing meahs for said heater and rheostat; whereby movement of said member to its said switchopening position establishes a circuit through said heater and said rheostat in shunt to the switch governed load for thereby rendering said heater operative thermally to energize the thermostat.

6. In a socket switch structure embodying a switch holding block, the combination with an electrical device arranged to be governed by said switch, of a lamp receptacle secured to said block, anouter casing arranged to inclose said structure and said receptacle, and a current-reducing resistance unit for said device comprising a drum of insulating and refractory material formed and positioned to encompass said receptacle interior of said casing, a winding of resistance wire about said drum with means for electrical connections thereof to said switch and to said device, and an outer covering of insulating and refractory material for said wire substantially as shown and described.

7. In an electric switch, the combination with main circuit controlling contacts normally adapted to open and associated control means arranged to be electro-thermally tion of said cam and whereby movement of said cam to its said switch-opening position energizes said thermostatic means for permitting said contacts automatically to open after a predetermined time.

8. In an electric switch, the combination with main circuit-controlling contacts and associated thermostatic control means arranged to be electro-thermally operated for governing the opening of said contacts, of a pivoted member progressively rotatable to consecutive positions thereof and adapted in said positions respectively to close and to cause opening or said contacts, and

a manually operable auxiliary device arranged as a ratchet for driving said member,

together with auxiliary circuit-controlling means connected electrically to govern said thermostatic means and positioned to be operated by said member; whereby said thermostatic means are deenergized in the said contact-closing position of said member and whereby movement of said member from its said contact-closing position energizes said thermostatic means for automatically causing said contacts to open after a predetermined time.

9. In a socket-switch structure, in combination; a switch having a spring-returned oscillatory pull element, a step-by-step rotatable current switching member operated thereby, and stationary contacts cooperatively arranged with circuit connections through the structure so that Successive strokes of said element; cause the switch alternately to be closed and to be opened;

and structure-contained electrically operated instrumentalities" arranged automatically to delay the opening of the switch for a substantial but limited interval of time after the stroke of said element adapted to cause said opening.

10. In a socket-switch structure, in combination; a button-like insulating block}; switch mechanism mounted on and operating above said block; a cylindrical receptacle secured to and depending from the under surface of said block; a sleeve-like resistance unit encompassing said receptacle and electrically connected to cooperate with said switch mechanism; and a cylindrical open-ended casing adapted to assemble telescopically with the socket-switch structure to inclose said switch mechanism, and to encompass both said block and said resistance unit,the said casing being of smaller diameter in its bottom portion than in its upper portion to form a shoulder, and said block being of substantially greater diameter'than said resistance unit to engage with and be supported by said shoulder.

Signed at Boston, in the county of Suffolk and Commonwealth of Massachusetts, this 20th day of October, 1915.-

MALCOLM H. BAKER. Witnesses R. D. SMITH, SILVIO AMoRoso. 

